We live at 8900 and ours is 9 weeks old today. Our pediatrician told us that babies will drop to their lowest O2 levels right around 2 weeks old. We had Apria healthcare come out and leave a SpO2 monitor at the house for an overnight study. It would record her O2 levels continually. Once we were able to see what her levels did for 12 hours we knew we didn't need it. I have a couple buddies that live in Leadville ~10,000 and they have had both experiences.

I would say if in doubt go for it, then you won't have to stress although the O2 stuff is a PITA. If you can get a monitor then you will know definitively. Let me know if you need a pediatrician too, we found a pretty good place in Denver West so it's a pretty easy trip from the hills.

Also, we were full term (came on our due date exactly) so I'm sure that played a part. Good luck with her.